Tube-bending machine



April 12 1927. 1,624,804

' T.'T: ROBINSON TUBE BENDING MACHINE Filed July 5, 1924 I V 2 sheets-sheet 2 and 53 of the clamp member side of the arbor this extension forms the shoulder 50", and about the shorter side is positioned a U-shaped clamp 53 of special form designed to hold the tube tightly within its seat or groove 52. The clamp is provided with legs 53 and 53 which cmbrace the shorter or offset portion 54 of the arbor and lie closely upon opposite sides thereof. A block 55 is mounted between the legs of the clamp, and upon one side, this block is substantially of Ushape form to fit in the U bend in the tube upon the side opposite the forming arbor, to securely clamp the tube in position as shown in Fig. 4;. A set screw 56 is mounted in a threaded opening in the web portion of the clamp and a pin 57 is inserted through an opening in the block 05, the pin being provided with eccentrically formed journal portions and 59 rotatable in openings in the legs 53* and 53 'of the clamp. This pin is provided with a projecting end or thumb turn 60, and it will be apparent that when the pin is rotated the part 57 will be moved eccentrically with respect to the axis of the journals 59 and 59 and the block 55 will thereby be drawn up snugly into the bend of the tube. The set screw may then be turned to draw the tube closely into its groove or seat 52, the screw bearing against the end ofthe arbor to bring about such action.

The particularly novel form of clamp above described is especially efficient for use in clamping a previously formed tbshaped tube to a forming arbor 50. The construction' of the clamp of this invention is especially adapted to decrease the amount of time necessary in the operation of the machine, by allowing rapid engagement and disengagement of the parts. It is obvious from the disclosure that it is only necessary to slightly loosen the set screw 56 and then to withdraw the pin 57 from the arms 53 and 53 and the block 55 by a movement up wardly in a direction away from the table 13, in order to disengage the parts. The block 55 may then be removed from its position within the bend of the previously formed tube and from between the arms 53 The reverse action will securely clamp another pre viously bent U-shaped tube into operative position. The tube is placed in position within the seat or groove 52 and the block 55 is slipped into the bend in the tube and between the arms of the clamp 53, being locked in place by insertion of the pin 57. The set screw 56 is then tightened and the parts are in position for the machine to produce the subsequent bend. The portions 58 and 59 of the pin 57 which are eccentric to the portion. thereof which passes through the block 55, causes the clamp to be adjustable so that the tube may be properly positioned within the seat or groove 52 before adjacent the arbor.

the set screw 56 is tightened. The block 55 being within the bend of the tube and contacting with substantially the entire interior periphery of the bend, positions the clamp relatively to the bend in the tube so as to equalize the clamping strain at this portion. The tube when clamped, therefore, is especially well supported against distortion because of the form of the groove 52 and the corresponding seat or groove which end which receives a mandrel G5 and is secured against movement during the bend ing operation. To the end of the mandrel which enters the tube a series of balls 66 may be secured, which are pivoted to each other and to the mandrel to permit relative movement between the parts whenthe tube is bent. To hold the wall of this end of the tube against the mandrel, inner and outer swiping blocks 95 and 96 are pivoted at 97 and 98 to a mandrel carrier 98, the swiping block 95 being shaped at its free end to enter the groove 52 in the forming arbor and to bear against the tube'wall closely Thisblock is held in position against the tube and kept free from contact with the bending arbor by the holding block 99. Likewise, a holding block 100 is provided to bear against the swiping block 96 and force it firmly against the wall of the tube. I i

The operation of my machine is as follows: i

With the forming table inthe position shown in Fig. 1, a tube which has previously been bent into U-shaped form is securely clamped in the seat or groove 52 by means of the block 55 and pin 57, and the set screw 56. The mandrel 65 is then moved forwardly and inserted in the fixed or shorter end of the tube. The swiping blocks are secured firmly against the tube wall by means of the holding blocks 99 and 100. The bending operation is then begunby slowly rotating the shaft 12 and forming table 13. By reason of the connections of the forming arbor with the table, the arbor is rotated about the pin 14; and the tube will, of course be carried with the arbor forming a bend adjacent the outer ends of the swiping blocks. The forming arbor at the point where the bend takes place adjacent. the pin 14 is formed in the shape desired for the inside of the bend. The balls 66 which enter the tube adjacent the bend prevent deformation of the Wall is properly supported at this point as well as supported by the wall of the groove 52 and the block 55, and the bending operation takes place smoothly and evenly without wrinkling the tube to a harmful degree.

I \Vhile I have shown and described a pre ferred embodiment of my invention, it will pin passing through the block and adapted to urge the latter against thetube.

2. In a tube bending machine, a bending arbor provided with a tube receiving groove, and means to hold a tube in said groove including a pressing block and an eccentrically mounted pin passing through said block and adapted for rotation to urge said block against the tube.

3. Ina tube bending machine, a bending arbor having a tubereceiving groove, and means to hold a bent tube in said groove, comprising a block to set into the bend of the tube and means to draw the block toward the arbor, comprising a clamp, and a pin eccentrically mounted on the clamp, and passing through said block. v 4. In a tube bending machine, a bending arbor having a tube receiving groove, and means to hold a bent tube in said. groove, comprising a block to set into the bend of the tube and means. to draw the block to-';

ward the arbor, comprising a clamp, and a pin eccentrically mounted on the clamp, and passing through saidblock, and means to move said clamp relatively to the arbor to hold the tube tightly in position.

5. 'Ina tube bending machine, a bending arbor having a tube receiving groove contoured to receive a bent tube, a clamp having parts embracing the arbor, and bein adjustable relatively to the arbor, a block adapted to be received in the bendvof the tube, and means for adjusting said block relatively to the clamp.

6'. In a tube bending n1achine, a bending arbor having a tube receivinggroove con toured toreceive a bent tube, a clamp having parts, embracing the arbor, and being adjustable relatively to the arbor, a block adapted to be'received in the bend of the tube, and eccentrically mounted means for adjusting said block relatively to the clamp; 7. In a tube bending machine, a bending arbor having a tube receiving groove contoured to receivea bent tube, a clamp having eccentrically mounted pin upon which said I block is rotatably mounted to adjust the latter relatively to the clamp.

In witness whereof, I have hereunto set my handthis 1st day of July, 1924;

THOMAS T. ROBINSON. 

